Ground rods are used by utility companies to earth ground equipment associated with power distribution systems, e.g. high tension towers and light poles, so as to prevent damage caused by lightning, electrical surges, stray voltages and the like. Typically, ground rods have been constructed of copper or other core material having a copper sheath.
Presently, it is customary to hammer or drive the rod into the earth by some sort of impacting device. If a copper rod is utilized as the ground rod, the repeated impacting may cause the end of the rod to flatten, due to its soft malleable nature, thereby limiting the depth to which the ground rod can be driven into the earth. If the end of the rod has been flattened, additional rods may not be able to be connected to the inserted rod (it is often necessary to drive several lengths of rods into the earth so as to obtain the desired or necessary grounding depth).
Another problem associated with conventional driving practices is that the friction caused by impacting may cause the rod to bend and/or deform, when the rod is being driven through more stubborn strata. This in turn makes it even more difficult to drive the rod into the ground. Furthermore, glancing blows to the rod may cause the rod to whip violently from side to side, creating the potential for injury to unwary bystanders or damage to nearby equipment.
Another method of inserting ground rods into the earth is by drilling or boring. This technique, however, typically requires the utility company to carry a drilling rig or the like to the site, which is a costly and time consuming process.
One example of a known ground rod pusher is illustrated in U.S. Pat. No. 2,327,616, issued Aug. 24, 1943 to Abramson et al. Abramson et al disclose a portable rod inserting device comprising a motor, bore assembly (collet and chuck) and supporting equipment. The motor imparts rotary motion to the bore assembly, which holds the rod, while manual downward pressure is exerted on a pair of handles which extend outwardly from the bore assembly. The bore assembly is fastened to the rod and pushed is downward until the bore assembly contacts the base of the apparatus. The bore assembly is then unfastened, moved back to the starting position and refastened to the rod and the procedure repeated. One end of the rod is also provided with a drilling head so as to precipitate the breaking of the surface of the soil. Furthermore, the apparatus can be used to insert several rods, which have been connected together, into the ground.
Accordingly, there is a current need to drive ground rods into the earth without the aforementioned problems or surplusage of equipment. The ability to reliably and easily drive a ground rod into the earth would result in substantial savings in time and materials while simultaneously allowing utility companies to obtain greater grounding connections by inserting several lengths of rods to thereby reach greater depths. To achieve this result, a device is required which is capable of inserting the ground rod by pushing (or pressing) rather than by drilling or repeatedly impacting.
The present invention provides a novel and improved device for pressing rods into the earth. The exemplary embodiment of this invention uses a plurality of pivotable pusher plates axially mounted on the exterior of a hollow pusher body. An elongated, slotted, hollow mast is provided, upon which the pusher body is slidably mounted and includes a tube which is sized and configured to stabilize the rod within the tool. The pusher plates are pivoted inwardly through slots so as to rest upon the top of a rod which has been previously inserted within the mast. A downward stroke from a prime mover, or other mechanical source, applies a downwardly directed pressing force and through the pusher body and pusher plates presses the rod into the earth.
The exemplary pushing tool may also be provided with a coupling tool. One end of the coupling tool is connected to the bottom of the tool and the other end is provided with a foot plate to support the tool while in use. The coupling tool serves to automatically align the pusher body and mast containing an additional rod, over a previously inserted rod so that one or more rods may be pushed or pressed into the earth.
The exemplary method of using the pushing tool comprises loading a rod into an elongated mast on which is mounted a moveable pusher body having plural pusher plates. A first pusher plate is pivoted inwardly so as to rest upon the top of the rod so that a downward stroke from a prime mover applies a pressing force to the pusher body, and through the first pusher plate, the rod is pushed into the earth a first distance. Once the first downstroke is complete, the pusher body is retracted so that the top of the rod is adjacent to a second pusher plate. Prior to the actuation of the prime mover for a second stroke, the second pusher plate is pivoted inwardly so as to rest upon the top of the rod. A second down stroke applies a pressing force to the pusher body and through the second pusher plate, the rod is driven into the earth a second additional distance. The pusher body is once again retracted so that the top of the rod is adjacent to the third pusher plate. The third pusher plate is now pivoted inwardly and a third down stroke is applied to the pusher body, and through the third pusher plate, the rod is fully driven into the earth.
It is appreciated that the axial distance between the pusher plates is substantially equal to the maximum distance traveled during a single downward stroke of the prime mover and that after each downward stroke the pusher body is retracted a substantially equal and opposite distance so as to be ready for the next actuation of the prime mover.
Other objects and advantages of the invention will become apparent from the detailed description which follows.